Engineering Prof. Computes Available Biofuel Crop Lands

Switchgrass (Agricultural Research Service/USDA)

A detailed land analysis by researchers at University of Illinois in Champaign found that biofuel crops cultivated on available land could produce up to half of the world’s current fuel consumption, without affecting food crops or grazing land for livestock. Engineering professor Ximing Cai and two colleagues published their findings last month in the journal Environmental Science and Technology.

Cai says there has been relatively little research on land availability, a key constraint in biofuel development, particularly in light of concerns over the impact of biofuel crops on food production. His research addresses those issues by identifying land worldwide available to produce grass crops for biofuels, with minimal impact on agriculture or the environment.

The researchers base their analysis on the availability of marginal land for biofuel crops, defined as land abandoned, degraded, or considered of low quality for agriculture. The focus on marginal land, therefore, ruled out current crop land, pasture land, and forests. They also assume that biofuel crops would be watered by rainfall and not irrigation, thus diverting no water from agricultural land.

Cai and his team used a mathematical modeling technique called fuzzy logic that enabled them to consider multiple scenarios for land availability. They began with only idle and vegetation land with marginal productivity, and then added for the second scenario, degraded or low-quality crop land. This second scenario led to an estimate of 702 million hectares (2.71 million square miles) of land available for second-generation biofuel crops, such as switchgrass (pictured left) or miscanthus.

The researchers then broadened their analysis to include marginal grassland. A class of biofuel crops called low-impact high-diversity (LIHD) perennial grasses could produce bioenergy while maintaining grassland. Cai says LIHD crops have a lower ethanol yield than grasses such as miscanthus or switchgrass, but they have minimal environmental impact and are similar to grassland’s natural land cover.

Adding LIHD crops grown on marginal grassland to the marginal crop land estimate from earlier scenarios expanded the estimated land area to 1,107 million hectares (4.27 million square miles) globally. This later estimate covers an area that could produce from 26 to 56 percent of the world’s current liquid fuel consumption.

Read more: Math Model Developed for Biofuels Development

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